(4R)-Ethyl 4-(4-chloro­phen­yl)-2-hydr­oxy-5-oxo-2,3,4,5-tetra­hydro­pyrano[3,2-c]chromene-2-carboxyl­ate

The title compound, C(21)H(17)ClO(6), is optically pure and adopts an R configuration. It was obtained by an organocatalytic asymmetric Michael addition of 4-hydroxy­coumarin with (E)-ethyl 4-(4-chloro­phen­yl)-2-oxobut-3-enoate. The structure consists of a tetra­hydro­pyran unit fused to the coumarin ring ring system. The hydroxyl and phenyl groups are on the same side of the tetra­hydro­pyrane ring. The benzene ring is almost perpendicular to the coumarin ring [dihedral angle of 72.89 (3)°]. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds are observed. An intra­molecular O—H⋯O contact also occurs.